CVE-2005-0592 in Firefox
Summary
by MITRE
Heap-based buffer overflow in the UTF8ToNewUnicode function for Firefox before 1.0.1 and Mozilla before 1.7.6 might allow remote attackers to cause a denial of service (crash) or execute arbitrary code via invalid sequences in a UTF8 encoded string that result in a zero length value.
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Analysis
by VulDB Data Team • 05/31/2019
The vulnerability identified as CVE-2005-0592 represents a critical heap-based buffer overflow flaw within the UTF8ToNewUnicode function of Mozilla Firefox and the broader Mozilla browser suite. This issue affects versions prior to Firefox 1.0.1 and Mozilla 1.7.6, creating a significant security risk that could be exploited by remote attackers to compromise system integrity. The vulnerability stems from inadequate input validation mechanisms within the UTF-8 decoding process, specifically when handling malformed UTF-8 sequences that result in zero-length values during the conversion from UTF-8 to Unicode representation.
The technical exploitation of this vulnerability occurs when the browser encounters invalid UTF-8 encoded strings during web page rendering or data processing operations. The UTF8ToNewUnicode function fails to properly validate the length calculations derived from malformed UTF-8 sequences, leading to memory corruption when attempting to allocate heap space for the converted Unicode output. This improper handling creates a condition where the application writes beyond the allocated buffer boundaries, potentially overwriting adjacent memory regions and causing unpredictable behavior. The vulnerability manifests as either a denial of service through application crash or more severely, arbitrary code execution when carefully crafted malicious input is processed by the affected browser components.
From an operational perspective, this vulnerability presents a substantial risk to end users who browse the internet without adequate security measures or up-to-date browser versions. Attackers can leverage this flaw by crafting malicious web pages containing specially formatted UTF-8 sequences that trigger the buffer overflow during normal browsing operations. The impact extends beyond simple service disruption to potentially enable full system compromise, as successful exploitation could allow attackers to execute arbitrary code with the privileges of the browser process. This makes the vulnerability particularly dangerous in environments where users may encounter untrusted web content or where automated exploitation techniques are available.
The vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and represents a classic example of improper input validation in string processing functions. From an ATT&CK framework perspective, this vulnerability maps to T1059.007 for command and scripting interpreter execution and T1499.004 for network denial of service, as it enables both crash-based denial of service and more sophisticated execution-based attacks. Mitigation strategies should include immediate deployment of security patches updating to Firefox 1.0.1 or Mozilla 1.7.6, implementation of web application firewalls that can detect and block malformed UTF-8 sequences, and regular security updates to prevent exploitation of similar vulnerabilities in other browser components. Organizations should also consider implementing browser hardening measures and monitoring for suspicious network traffic patterns that might indicate exploitation attempts against this class of vulnerability.